SURGICAL DISTRACTOR AND DELIVERY INSTRUMENT
A surgical distractor for distracting a joint space to facilitate passage of a surgical tool. The distractor includes a first arm, a second arm, a coupling device, and a limit device. Each arm includes a handle portion and a flange. The coupling device pivotably couples the first and second arms such that the flanges combine to define a passage. A size of the passage increases when transitioning the distractor from a first state of expansion to a second state of expansion. The limit device is associated with the arms for selectively preventing transitioning of the distractor from the second state of expansion to the first state of expansion. In some embodiments, the flanges, and thus the passage, is laterally and/or angularly offset from the handle portions.
The subject matter of this application is related to the subject matter of U.S. Provisional Application Ser. No. 60/846,944, filed Sep. 25, 2006 and entitled “Prosthesis Insertion Instrument;” priority to which is claimed under 35 U.S.C. §119(e) and an entirety of which is incorporated herein by reference.
BACKGROUNDThe present disclosure relates to surgical devices and methods associated with facilitating delivery of surgical tools to a bodily joint, for example implanting a spinal prosthetic into a spinal disc space.
Many surgical procedures entail accessing an enclosed anatomical structure, such as a bodily joint, and delivering a surgical tool to the enclosed area. For example, prosthetic implants are commonly used for repairing a plethora of different anatomical structures and joints. Implanting a spinal prosthesis is representative of the difficulties associated with many of these procedures. As a point of reference, the vertebrate spine is the axis of the skeleton on which all of the body parts “hang.” In humans, the normal spine has seven cervical, twelve thoracic and five lumbar segments. The lumbar spine sits upon the sacrum, which then attaches to the pelvis, and in turn, is supported by the hip and leg bones. The bony vertebral bodies of the spine are separated by intervertebral discs, which act as joints but allow known degrees of flexion, extension, lateral bending, and axial rotation.
The typical vertebra has a thick anterior bone mass called the vertebral body, with a neural (vertebral) arch that arises from the posterior surface of the vertebral body. The centra of adjacent vertebrae are supported by intervertebral discs. Each neural arch combines with the posterior surface of the vertebral body and encloses a vertebral foramen. The vertebral foramina of adjacent vertebrae are aligned to form a vertebral canal, through which the spinal sac, cord, and nerve rootlets pass. The portion of the neural arch which extends posteriorly and acts to protect the spinal cord's posterior side is known as the lamina. The spineous process projects from the posterior region of the neural arch.
The intervertebral disc primarily serves as a mechanical cushion permitting controlled motion between vertebral segments of the axial skeleton. The normal disc is a unique, mixed structure, comprised of three component tissues: the nucleus pulpous (“nucleus”), the annulus fibrosus (“annulus”) and two vertebral end plates. The two vertebral end plates are composed of thin cartilage overlying a thin layer of hard, cortical bone which attaches to the spongy, richly vascular, cancellous bone of the vertebral body. The end plates thus act to attach adjacent vertebrae to the disc. In other words, a transitional zone is created by the end plates between the malleable disc and the bony vertebrae.
The annulus of the disc is a tough, outer fibrous ring which binds together adjacent vertebrae. The fibrous portion, which is much like a laminated automobile tire, measures about 10 to 15 millimeters in height and about 15 to 20 millimeters in thickness. The fibers of the annulus consist of fifteen to twenty overlapping multiple plies, and are inserted into the superior and inferior vertebral bodies at roughly a 40-degree angle in both directions. This configuration particularly resists torsion, as about half of the angulated fibers will tighten when the vertebrae rotates in either direction, relative to each other. The laminated plies are less firmly attached to each other. The nucleus is immersed within the annulus, positioned somewhat like the liquid core of a golf ball. The healthy nucleus is largely a gel-like substance having high water content, and like air in a tire, serves to keep the annulus tight yet flexible. The nucleus-gel moves slightly within the annulus when force is exerted on the adjacent vertebrae while bending, lifting, etc.
The spinal disc may be displaced or damaged due to trauma or a disease process. A disc herniation occurs when the annulus fibers are weakened or torn and the inner tissue of the nucleus becomes permanently bulged, distended, or extruded out of its normal, internal annulus confines. The mass of a herniated or “slipped” nucleus tissue can compress a spinal nerve, resulting in leg pain, loss of muscle control, or even paralysis. Alternatively, with discal degeneration, the nucleus loses its water binding ability and deflates, as though the air had been let out of a tire. Subsequently, the height of the nucleus decreases causing the annulus to buckle in areas where the laminated plies are loosely bonded. As these overlapping, laminated plies of the annulus begin to buckle and separate, either circumferential or radial annular tears may occur, which may contribute to persistent and disabling back pain. Adjacent, ancillary spinal facet joints will also be forced into an overriding position, which may create additional back pain.
Whenever the nucleus tissue is herniated or removed by surgery, the disc space will narrow and may lose much of its normal stability. In many cases, to alleviate back pain from degenerated or herniated discs, the nucleus is removed and the two adjacent vertebrae are surgically fused together. While this treatment alleviates the pain, all discal motion is lost in the fused segment. Ultimately this procedure places a greater stress on the discs adjacent to the fused segment as they compensate for lack of motion, perhaps leading to premature degeneration of those adjacent discs.
As an alternative to vertebral fusion, a prosthetic spinal disc nucleus device can be implanted into the disc space, such as the HydraFlex™ nucleus replacement device available from Raymedica, LLC of Bloomington, Minn. With these and other spinal nucleus prostheses, the implantation procedure generally entails forming a passage through the annulus for insertion of the prosthesis. One surgical concern is the potential damage imparted upon the annulus during implantation surgery. The normal annular plies act to keep the annulus tight about the nucleus. During prosthetic nucleus implantation surgery, a surgical knife or tool is used to completely sever some portion of the annulus and/or remove an entire section or a “plug” of the annulus tissue. Adjacent vertebrae are often distracted, or spread apart, with a spinal implant fitted in the annular space. During distraction and implant insertion additional damage to the remaining annulus, as well as the vertebral endplates can occur. Additionally, when an entire section of the annulus is cut or removed to insert an implant, the layers making up the annulus often “flay” and/or “pull back” and the constraining or tightening ability of that portion of the annulus is lost. Similar concerns arise with numerous other prosthetic implantation procedures apart from the spinal disc, as well as with many bodily joint preparation procedures. More generally, then, surgeons have a need for surgical tools and methods that facilitate distraction of, and access to, an anatomically closed space (e.g., a joint) in a non-traumatic fashion.
SUMMARYSome aspects of the present disclosure relate to a surgical distractor for distracting a joint space so as to facilitate, for example, passage of a surgical tool into the joint space. With this in mind, the distractor includes a first arm, a second arm, a coupling device, and a limit device. Each of the arms includes a handle portion and a flange. The coupling device pivotably couples the first and second arms such that the flange of the first arm is adjacent the flange of the second arm. With this construction, the flanges combine to define a passage, with the distractor being configured to provide at least first and second states of expansion. In this regard, a size of the passage increases in transitioning of the distractor from the first state of expansion to the second state of expansion. Finally, the limit device is associated with the arms for selectively preventing transitioning of the distractor from the second state of expansion to the first state of expansion. In some embodiments, the flanges, and thus the passage, are laterally and/or angularly offset from the corresponding handle portions. In yet other embodiments, each of the arms further forms a contact face positioned proximally of, and extending transversely beyond, the corresponding flange.
Other aspects of the present disclosure relate to a method of surgically interfacing with a bodily joint. The method includes providing a surgical distractor including opposing arms each having a flange that combine to define a passage. The distractor device is transitionable between at least a first state of expansion and a second state of expansion, with a size of the passage being greater in the second state of expansion as compared to the first state of expansion. With this in mind, the distractor is arranged in the first state of expansion, and the flanges are introduced through an access site of the bodily joint. A distraction force is applied to the bodily joint by forcibly transitioning the distractor from the first state of expansion to the second state of expansion. Finally, the bodily joint is accessed via the passage. In some embodiments, the flanges combine to define a reverse wedge shape in transitioning to the second state of expansion, thereby drawing the flanges into the bodily joint. In yet other embodiments, the bodily joint is a spinal disc space, and accessing the bodily joint includes implanting a spinal nucleus prosthesis into the disc space via the passage.
In view of the above background, various distractor, anatomical access tools, implantation system, and implantation method objectives and advantages have been identified, with some embodiments of the present disclosure addressing distractors, anatomical access tools, implantation systems, and methods of prosthetic implantation that are characterized by one or more of the following: forming a passage through which surgical tool(s) (e.g., prosthesis, surgical instrument, etc.) can pass into an anatomically closed structure (e.g., a bodily joint such as a nucleus cavity); being substantially atraumatic to anatomical structural elements (e.g., endplates of a spinal disc space); for procedures entailing implantation of a prosthesis, reducing the force required to insert an implant into anatomically closed structure (e.g., bodily joint such as the nucleus cavity); substantially reducing or substantially preventing expansion of a joint access incision (e.g., an annulotomy); and/or substantially reducing a need for, or substantially obviating fixation on anatomy surrounding the bodily joint. In particular, it should be understood that various other objectives and advantages are also contemplated, and that the examples presented above are not exclusive.
The first arm 22 defines a first handle portion 28, a first hinge portion 30, and a first jaw portion 32. In some embodiments, the first arm 22 is optionally formed as a substantially monolithic, or unitary, piece. However, a plurality of separate, connected components, including separate, connected subcomponents associated with the first handle portion 28, the first hinge portion 30, and/or the first jaw portion 32, are used in other embodiments.
In some embodiments, the first handle portion 28 is substantially elongate and is generally adapted for grasping, for example including various ergonomic or other grasping/handling features. The first handle portion 28 optionally has indentations 34 formed over a portion thereof for ease and surety of grasping. For reference, a length of the first handle portion 28 can be selected according to a desired mechanical advantage, among additional or alternative design considerations. The first handle portion 28 defines a proximal end 36 of the first handle portion 28, with a slot 38 and shaft hole 40 formed toward the proximal end 36 of the first handle portion 28. The slot 38 is adapted to receive part of the limit arm 26 and the shaft hole 40 provides part of means for rotatably connecting the limit arm 26 to the first arm 22 as seated in the slot 38.
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In some embodiments, the second handle portion 80 is also substantially elongate and is generally adapted for grasping, for example including various ergonomic or other grasping/handling features similar, or different from the first handle portion 28 as desired. A length of the second handle portion 80 can also be selected according to a desired mechanical advantage, among additional or alternative design considerations. The second handle portion 80 defines a proximal end 86.
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In some embodiments, the distractor 20 is configured such that in the first state of expansion, a maximum size (e.g., height) of the passage 150 is commensurate with or smaller than that of a surgical tool (not shown) to be used with the distractor 20 in performing a particular procedure (e.g., a prosthesis).
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The distractor 20 is also configured to provide a third state of expansion in which a maximum opening size of the passage 150 is greater than that of the second state of expansion. As referenced above, in some embodiments, the first and second flanges 60, 102 are angled to “flare away” from one another in at least the second and/or third states of expansion via shapes of the flanges 60, 120 and location of the hinge point (i.e., the pin 120). If desired, the distractor 20 can be configured such that the first and second flanges 60, 102 optionally extend substantially parallel to one another, or even toward one another, in the first state of expansion to facilitate insertion of the first and second flanges 60, 102 into a surgical incision, with distraction of the joint in question occurring upon transition to the second and/or third states of expansion, as described in greater detail below. Alternatively, the distractor 20 can be configured such that the first and second flanges 60, 102 extend away from one another in the first state of expansion.
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The distractor 20 can be used in performing a wide variety of surgical procedures in which access to and/or distraction of an anatomically closed structure, such as a bodily joint, is required. One non-limiting example is in connection with implantation of a nucleus prosthesis into a spinal disc space. One such procedure is described in detail in U.S. Provisional Application Ser. No. 60/846,944, filed Sep. 25, 2006, the teachings of which are incorporated herein by reference. In general terms, and with reference to
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In the second (or third) state of expansion, a prosthetic spinal disc nucleus (not shown) is then delivered through the passage 150 and distally into the disc space 200. In this regard, one or more additional surgical tools or instruments can be delivered through the passage 150 to assist in desired placement of the prosthesis. The off-set longitudinal positioning of the flanges 60, 102 relative to the corresponding handle portions 28, 80 locates the handle portions 28, 80 away from the surgical site (e.g., the hole 208) such that the surgeon's view of the surgical site is only minimally obstructed. Where desired or necessary, the distractor device 20 can be further transitioned from the second expansion state to the third expansion state to effectuate enhanced distraction of the vertebrae 202a, 202b. Upon completion of the procedure, the limit arm 26 is disengaged, allowing the distractor 20 to revert to the first expansion state. The distractor 20 can then be removed from the disc space 200.
As referenced above, in some embodiments use of the distractor 20 provides a smooth sliding surface (e.g., the inner surfaces 72, 110 shown in
Although the present disclosure has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes can be made in form and detail without departing from the spirit and scope of the present disclosure.
Claims
1. A surgical distractor for distracting a joint space to facilitate passage of a surgical tool into the joint space, the distractor comprising:
- a first arm including a handle portion and a flange;
- a second arm including a handle portion and a flange;
- a coupling device pivotably coupling the first and second arms, with the flange of the first arm being adjacent the flange of the second arm;
- wherein the flanges combine to define a passage and the surgical distractor is configured to provide a first state of expansion and a second state of expansion, a size of the passage being greater in the second state of expansion than in the first state of expansion; and
- a limit device associated with the arms for selectively preventing transitioning of the distractor from the second state of expansion to the first state of expansion.
2. The distractor of claim 1, wherein each of the flanges are laterally offset from the corresponding handle portions.
3. The distractor of claim 2, wherein the handle portions combine to define a first longitudinal axis and the flanges combine to define a second longitudinal axis, and further wherein the first longitudinal axis is laterally offset from the second longitudinal axis.
4. The distractor of claim 3, wherein the first and second longitudinal axes are parallel.
5. The distractor of claim 3, wherein the first and second longitudinal axes are non-parallel such that the passage is angularly offset relative to the handle portions.
6. The distractor of claim 1, wherein a pivot point of the first and second arms is formed intermediate the respective flanges and handle portions such that each of the flanges extend distally relative to the pivot point from a proximal side to a distal side, and further wherein each of the flanges project transversely outwardly in distal extension from the proximal side to the distal side in at least the second state of expansion.
7. The distractor of claim 1, wherein each of the flanges are U-shaped in transverse cross-section.
8. The distractor of claim 1, wherein at least a portion of the passage is arcuate in transverse cross-section.
9. The distractor of claim 1, wherein each of the arms further includes a transition disposed between the corresponding flange and the handle portion, the transition defining a contact face extending transversely beyond the corresponding flange.
10. The distractor of claim 9, wherein the transition establishes a transverse offset of the flange relative to the corresponding handle portion.
11. The distractor of claim 1, wherein the distractor is configured such that the flanges combine to define a reverse wedge shape in at least the second state of expansion.
12. The distractor of claim 1, wherein the limit device includes a limit arm pivotably coupled to the first arm.
13. The distractor of claim 12, wherein the limit device further includes a pin extending from the limit arm, and further wherein the handle portion of the second arm forms a seat sized to selectively receive the pin.
14. A method of surgically interfacing with a bodily joint, the method comprising:
- providing a surgical distractor including: a first arm including a handle portion and a flange, a second arm including a handle portion and a flange, a coupling device pivotably coupling the first and second arms, with the flange of the first arm being adjacent the flange of the second arm, wherein the flanges combine to define a passage and the surgical distractor is configured to provide a first state of expansion and a second state of expansion, a size of the passage being greater in the second state of expansion than in the first state of expansion, a limit device associated with the arms for selectively preventing transitioning of the distractor from the second state of expansion to the first state of expansion;
- arranging the distractor in the first state of expansion;
- introducing the flanges through an access site of the bodily joint;
- applying a distraction force to the bodily joint by forcibly transitioning the distractor to the second state of expansion; and
- accessing the bodily joint via the passage.
15. The method of claim 14, wherein applying a distraction force includes arranging the flanges to define a reverse wedge shape to draw the flanges into the bodily joint.
16. The method of claim 14, wherein each of the arms further includes a contact face proximal the corresponding flange, and further wherein introducing the flanges includes abutting the contact faces against an anatomical structure of the bodily joint.
17. The method of claim 14, wherein the flanges are laterally offset from the corresponding handle portions, and further wherein accessing the bodily joint includes inserting a surgical tool through the passage, with a proximal portion of the surgical tool being adjacent the handle portions.
18. The method of claim 14, wherein the bodily joint is a spinal disc space.
19. The method of claim 18, wherein accessing the bodily joint includes implanting a spinal nucleus prosthesis into the disc space via the passage.
20. The method of claim 18, wherein applying a distraction force is characterized by the absence of a fixed connection between the distractor and anatomy outside of the disc space.
Type: Application
Filed: Sep 25, 2007
Publication Date: Mar 27, 2008
Inventor: Erik Emstad (St. Paul, MN)
Application Number: 11/861,010
International Classification: A61B 17/58 (20060101);